Who are the best solar companies in Illinois?

Search for solar companies in Illinois and you get "best of" lists. We read the ones we could open on October 25, 2026. Some earn a commission when you click a "get quotes" button. One ranked its own company first. That day, one quote marketplace said it works with nine Illinois installers. The state shows 134 Approved Vendors signed home customers in 2025. None sent readers to the state's vendor, violation or complaint reports.

That is a problem, because the best company for you depends on three things a list cannot see. They are your roof, how you pay, and whether the company works at your address. A star score built from national surveys says little about any of them.

Illinois records can answer what a list cannot.

Google and review sites show stars. A 4.9 from 20 reviews feels safe. It is not very safe. Type a company's counts below to see the range its real score could fall in.

Use the total and the number of 4 and 5 star reviews. It cannot tell whether reviews are real or picked by the company. Weigh it with the state's records, not instead of them.

Illinois Shines is the state's solar incentive program. Companies that want to sell solar through it must register. You can read what the state keeps on them.

We do not repeat the click-by-click steps here. Our guide to checking an Approved Vendor walks through them. This page is about what to do with the records: how to turn a long list into three names.

What do "Approved Vendor" and "Designee" mean?

They are not the same, and that matters when a salesperson knocks.

In 2025 the program logged 457 complaints about Approved Vendors and 373 about Designees. So check both. In person, the seller has to tell you which company they represent, and the Approved Vendor's name if they work for a Designee.

Solar power companies in Illinois look plentiful on paper. The state's August 2026 data report counts 1,066 Approved Vendors and 858 Designees registered since 2019. Many have closed, merged or never sold much.

The 2025 complaint report gives a truer count. 134 Approved Vendors had a customer sign a home-system Disclosure Form in 2025. That is the list you are really choosing from.

Read that chart with care. The report says the 23.1% of vendors that had at least one complaint filed 95% of the program's project applications. So "no complaints" mostly belongs to companies with few customers.

The better test uses the report's own table. For each large Approved Vendor it lists the share of all complaints and the share of all applications. A company with 5% of the complaints and 5% of the projects looks typical. A company with 20% of the complaints and 5% of the projects does not. For example, with made-up numbers: 10 complaints on 200 projects is a rate of 1 in 20. The same 10 on 2,000 projects is 1 in 200.

Designees look similar. Of 243 Designees that signed home customers in 2025, 81.5% had no complaint.

The program received 832 complaints in 2025, down from 1,123 in 2024. Customers can file one by web form, phone or email.

Two facts help you shop.

• Companies that closed drew a big share. 203 832 complaints (24%) named companies that had closed or cut back. 21 such companies drew complaints. In 2024 that share was 61%. The yearly complaint report names them.
• How a company answers is the real test. By the end of 2025, 346 complaints were resolved and 305 were closed. In 228 of the closed ones, the company or the customer stopped answering. In 77 the company answered but the problem stayed unsolved.

So pick a company that will still be there in year 10, and test how it treats a question before you sign. Our guide to a solar company that went bankrupt covers what to do if it happens anyway.

Here is the method. It takes an evening and a few phone calls.

1. 1
   Collect six to eight names.

   Ask neighbors with panels what they would do differently. Look up any company you hear about on the Approved Vendor list. If your household is income-eligible, use the Illinois Solar for All installer directory, which you can filter by county. Illinois Solar Map is a civic data site that counts projects by county from the state's application reports. It shows volume, not quality.

2. 2
   Cross out the ones that fail the records.

   Cross off any company that is not listed, is color-flagged as suspended or inactive, or has no Illinois Commerce Commission certification for its installer.

3. 3
   Read the complaint reports.

   Use the share test above. Look at what the company did after each complaint.

4. 4
   Call each one with five questions.

   Who is your Approved Vendor? Does your own crew install, or do subcontractors? Do you work at my address and on my kind of roof? Who services the system in year 8, and what happens if you close? Can I have the Disclosure Form and a written quote before I decide?

5. 5
   Get three written quotes, each with its Disclosure Form.

   The state's own advice for its income-eligible program is at least three quotes. Then compare them line by line with our quote checklist.

A company that dodges question 4 or question 5 just saved you time.

Companies that use Illinois Shines must follow the state's Consumer Protection Handbook. Here is what the 2026-27 version says that you can use on a phone call or at the door.

If a seller breaks these rules, note the date and company and report it. The verify guide lists where. A company outside the program is not bound by these rules, which is one more reason to ask.

Panels last decades. Companies do not always. Three state tools exist because that is a real risk. The Solar Restitution Program launched May 6, 2025. The escrow process, which can hold an Approved Vendor's credit payments for customers, launched June 26, 2025. A stranded-customer credit adder launched October 23, 2025.

You can plan for it. Ask which maker backs the panels and the inverter, because those warranties usually come from the maker, not the installer. Ask who services the system if the installer closes. Avoid paying the whole price early. Our loan fee guide shows how to check the cost of financing, and the lease or buy guide shows what changes if someone else owns the panels.

The best installer cannot fix a bad roof. Pause before you collect quotes if any of these is true:

• Your roof needs replacing within about ten years. Replace it first. Panels have to come off and go back on. See what the roof needs.
• Trees or buildings shade the roof. Get the shade measured before any quote. See solar on a shaded roof.
• You rent, or your condo board controls the roof. Rooftop solar is not yours to decide. Community solar may fit. Read what Illinois law says about HOAs.
• Your household is income-eligible and you own your home. Start with Illinois Solar for All, which has its own installer list and a free eligibility lookup.
• Your electric bill is small. Payback takes longer. Run our payback calculator before you spend an evening on quotes.

If none of that applies, check your roof first. The free solar check on this page looks at the roof and says plainly if it is not a fit. That saves you from taking calls you do not need.